Date:	Sun, 16 Nov 1997 12:42:36 +0000 ( )
From:	"Gurunandan R. Bhat" <grbhat AT unigoa DOT ernet DOT in>
To:	Mithrandir <434667 AT cepsz DOT unizar DOT es>
Cc:	djgpp AT delorie DOT com
Subject:	Re: Interrupt hooking help, please
In-Reply-To:	<347098B8.35F3@cepsz.unizar.es>
Message-Id:	<Pine.LNX.3.91.971116123610.297A-100000@aditya.unigoa.ernet.in>
Mime-Version:	1.0

On Mon, 17 Nov 1997, Mithrandir wrote:

> I need to hook the timer interrupt. I also need have it called 16000
> times a second (a very high rate, I know).

Try this:

      <URL: ftp://ftp.coast.net/SimTel/msdos/c/pctime13.zip>
Program written by: Chih-Hao Tsai (c-tsai4 AT uiuc DOT edu)      11/26/95

> I have read in a document
> called DJGPPASM.DOC that I should use a real mode interrupt.

That is unfortunately, easier said than done. It involves writing 16-bit
code and makes memory access difficult. I have a very rudimentary real
mode handler and would be happy to share it when complete. A more
reasonable (though not efficient) method is to write a real mode
*callback* (see excellent discussion in the FAQ Sec 18). pctime13.zip has
routines that do this.  There was also some discussion on pctime13 on this
mailing list a week ago (check the archives)

I hope this helps.

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